A first wireless communication system including a transmission device and a reception device is known. In the first wireless communication system, the transmission device repeatedly transmits a wireless signal to the reception device. In the first wireless communication system, for example, as the transmission device moves, there are cases where communication between the transmission device and the reception device is not temporarily executable due to presence of an obstacle.
Thus, a second wireless communication system 900 disclosed in Patent Literature 1 (Japanese National Publication of International Patent Application No. 2012-500084) and Patent Literature 2 (Japanese National Publication of International Patent Application No. 2012-513698), as illustrated in FIG. 1, includes a transmission device 901, a reception device 902, and a relay device 903 and is configured to execute direct communication and indirect communication. The direct communication is communication for directly transmitting a wireless signal from the transmission device 901 to the reception device 902 not through the relay device 903. On the other hand, the indirect communication is communication for indirectly transmitting a wireless signal from the transmission device 901 to the reception device 902 through the relay device 903. Each of the transmission device 901 and the relay device 903 is mounted to a human body BD.
Accordingly, even in a case where the direct communication is not executable, the second wireless communication system 900 can transfer a wireless signal from the transmission device 901 to the reception device 902 by executing the indirect communication. In other words, it can be avoided that a time during which the reception device 902 can not receive a wireless signal from the transmission device 901 becomes excessively long.